Threaded fastener captivating device

ABSTRACT

A SNAP-IN SCREW CAPTIVATING DEVICE IS INSERTED INTO A HOLE IN SHEET MATERIAL TO BE SECURED BY THE SCREW AND IS FORMED OF RESILIENT MATERIAL IN THE GENERAL CONFIGURATION OF A SLOTTED CYLINDER HAVING A SCREW HEAD RECEIVING CHAMBER. THE CAPTIVATING DEVICE FITS WITHIN THE HOLE IN THE SHEET MATERIAL AND EXPANDS TO ENGAGE THE E EDGES OF THE HOLE. THE UPPER EDGES OF THE CHAMBER BEND INWARDLY A SHORT DISTANCE INTO THE CHAMBER TO FORM A LEDGE, AND THE SCREW IS PUSHED PAST THIS SLOTTED LEDGE CAMMING IT OUTWARDLY TO ALLOW THE HEAD TO PASS, WHEREUPON THE CHAMBER RESUMES ITS ORIGINAL POSITION. THE CHAMBER MAY BE EXTENDED TO PERMIT BACKING OUT OF THE SCREW FROM THE THREAD AND TO PROVIDE SPACE FOR A SNAP BUTTON TO BE PLACED ON TOP OF THE SCREW HEAD. WHEN THE BUTTON IS IN PLACE, THE BUTTON ALSO IS CAPTIVATED BY THE ACTION OF THE CAPTIVATING DEVICE HOLDING THE BUTTON IN PLACE.

Feb. 9, 1971 I I ,4; SELINKO 3,561,075

T HREADED FASTENER CAPTIVATING DEVICE Filed July 15, 1969 INVENTOR. GEORGE J. SELI NKO lam qefm/f qaiwug ATTORNEYS.

United States Patent U.S. Cl. 24-217 9 Claims ABSTRACT OF THE DISCLOSURE A snap-in screw captivating device is inserted into a hole in sheet material to be secured by the screw and is formed of resilient material in the general configuration of a slotted cylinder having a screw head receiving chamber. The captivating device fits within the hole in the sheet material and expands to engage the edges of the hole. The upper edges of the chamber bend inwardly a short distance into the chamber to form a ledge; and the screw is pushed past this slotted ledge camming it outwardly to allow the head to pass, whereupon the chamber resumes its original position. The chamber may be extended to permit backing out of the screw from the thread and to provide space for a snap button to be placed on top of the screw head. When the button is in place. the button also is captivated by the action of the captivating device holding the button in place.

BACKGROUND OF THE INVENTION In the mounting of sheet material such as a printed circuit board to a frame or base, it often is desired to secure the material by means of a threaded fastener in the form of a screw passing through a hole in the material. In some environments in which the printed circuit board may be mounted, vibrations of the like cause loosening of the screws to the point Where the printed circuit board no longer is securely mounted or the screws fall out, and get lost, or at disassembly the screw may be lost. Thus, it is desirable to provide a means for captivating the screws once they are in place to prevent this.

In addition, it often is desirable to mount additional components at a predetermined spacing relative to the circuit board, so that it generally is necessary to provide a separate fastening means mounted on the circuit board in order to support these additional components.

SUMMARY OF THE INVENTION Accordingly it is an object of this invention to provide a new and improved fastener captivating device.

It is an additional object of this invention to captivate a fastener for securing sheet material by means of a resilient member attached to or inserted into a hole in the sheet material and including a chamber for receiving the head of the threaded fastener, with a portion of the material extending over the head of the fastener when it is inserted into the captivating device to secure the fastener therein.

It is an additional object of this invention to provide a combination fastener captivating device and a snap receptacle for a mounting button.

In accordance with a preferred embodiment of this invention, a fastener captivating device is in the form of a hollow, slotted, resilient member having a shank portion extending into and engaging the sides of a hole in sheet material to be secured by the fastener. An upper fastener head receiving portion opens into the shank portion and has a ledge extending a short distance inwardly from the other edge thereof at an angle extend ing downwardly toward the center of the head receiving 3,561,075 Patented Feb. 9, 1971 portion. A fastener to be captivated is inserted into the opening in the ledge, and the head is pushed past the ledge which is slotted to expand to permit the fastener to be inserted into the head receiving portion. Once the head is pushed past the ledge, the resiliency of the material causes the member to resume its original configuration.

The sides of the head receiving portion are extended so that the edge of the ledge does not engage the top of the fastener but permits clearance for backing out of the fastener and also provides clearance for the insertion of a snap button over the fastener. The dimensions of the captivating membr are such that the ledge securely engages a shoulder on the button; so that the cooperation of the button with the member provides a fastener captivating device. Additionally the member also performs the function of anchoring the button in place over the fastener, so that the additional components may be mounted on the button.

BRIEF DESCRIPTION OF THE DRAWINGS Fig 1 is a perspective view of a captivating device formed in accordance with a preferred embodiment of this invention;

FIG. 2 is a cut-away side view of the device shown in FIG. 1, with a fastener located therein;

FIG. 3 is a top view of the device shown in FIG. 1;

FIG. 4 is a side view of a snap button to be used in conjunction with an embodiment of the device shown in FIGS. 1, 2 and 3; and

FIG 5 is a partially cut-away side view of another embodiment of the device shown in FIGS. 1, 2 and 3 showing the use of the device to captivate a fastener and to hold the snap button shown in FIG. 5.

DETAILED DESCRIPTION Referring now to the drawing, wherein like reference numerals are used throughout the several views to designate the same elements, there is shown a snap-in screw captivating device formed of resilient material such as relatively rigid plastic, metal or the like in the form of a member 10. The member 10 includes a cylindrical shank portion defined by the wall 11 and an upper fastener head receiving portion or chamber defined by the wall 12. A vertical slot 13 is formed in the member 10, so that the member may be compressed for insertion into a hole in a sheet to be fastened by the threaded fastener which the member is to captivate.

At the lower edge of the shank portion, the wall 11 flares outwardly to form a rib 14, the upper surface of which forms a shoulder 15 for engaging the lower surface of the sheet material into which the member 10 is to be inserted. The lower surface 17 of the wall forming the bottom of the chamber defined by the wall 12 rests on the upper surface of the sheet material into which the member is inserted, so that the distance A between the surface 17 and the shoulder 15 is equal to the thickness of the sheet material. When the member 10 is inserted into the sheet material, the resiliency of the member causes the member to attempt to expand to its original shape. This causes the member to securely engage the edges of the hole in the sheet material, since the hole is chosen to be a slightly smaller diameter than the outside diameter of the shank portion of the member defined by the wall 11 when the member is in its unrestrained configuration. If the member 10 is made of metal, it may be preferable to use a metal cup eyeleted to the hole in place of the one-piece snap-in device shown.

A top ledge 18 extending over and into the chamber defined by the side wall 12 is formed by extending the side wall 12 inwardly toward the center of the chamber at an angle of approximately 45 from the vertical surface of the side wall 12. This top ledge 18 is provided with additional slots 19 and 20, and the diameter C of the circle formed by the edge of the top ledge is chosen to be less than the width of the screw head with which the captivating member 10 is to be used. The distance B extending from the innermost edge of the ledge 18 to the bottom of the cavity defined by the side wall 12 is chosen to be such that, with the screw head in place and with the addition of a suitable Washer if desired, the innermost edge of the ledge 18 extends over the head of the screw as shown in FIG. 2, thereby captivating the screw and preventing its loss, while providing sufiicient clearance to disengage the threads of the screw from the material to which the sheet is mounted.

After the captivating member 10 is installed in the sheet material, the screw is pushed past the slotted edge 18, with the downward sloped camming surface of the ledge 18 being acted upon by the outermost edges of the head of the screw to expand the opening C to permit passage of the screw head therethrough. Once the head has passed through the opening, the resiliency of the material out of which the member 10 is formed causes it to tend to return to its original shape, thereby closing the opening over the screw head, with the edges of the ledge 18 engaging over the upper surface of the screw head to captivate the screw in place. The opening C is of sufiicient width to permit insertion of a screwdriver, or the like, for turning the screw in order to secure the screw to the material to which the sheet material is to be mounted.

Referring now to FIG. 4 there is shown a side view of a cylindrically shaped stud or snap button 21 which is utilized with a snap receptacle of the type provided by the member 10 shown in FIGS. 1, 2 and 3, and capable of being anchored by the member 10, so that components may be attached to the button as desired. The shank of the snap button 21 flares outwardly at its lower end and has the lower surface thereof in a concave shape having a configuration generally conforming to the head of a screw with which the button 21 may be used. The flared out portion includes a camming surface 22 and an upper shoulder surface 23, with the angle of the camming surface 21 being such as to cooperate with the angle of the ledge 18 on the member 10 to spread the upper portion of the chamber of the captivating device outwardly as the snap button is inserted into the chamber.

If the member 10 is to be utilized to both captivate a screw in the manner shown in FIG. 2 and further to provide a mounting base for the snap button 21, the chamber defined by the wall 12 may be enlarged in a vertical direction in order to accommodate the snap button 21. A member 10 having such an enlarged chamber is shown in FIG. which also shows the relative positions occupied by a screw 16 and the snap button 21 when both the screw and the button are inserted into the member 10. When the components are inserted as shown in FIG. 6, the member performs the dual function of captivating the screw 16 in its fully inserted position and additionally providing an anchoring base for the snap button 21.

In FIG. 5 the member 10 further is shown inserted into a circuit board 25, illustrating the manner in which the flange 14 and the surface 17 cooperate with the printed circuit board 25 to secure the member 10 in position within the hole in the printed circuit board 25. With the member 10 secured to the printed circuit board 25, the snap button 21 also is secured relative to the board and provides a mounting shoulder 26 formed by reducing the diameter of the shank or the body of the snap button 21 at its upper end.

The reduced shank 27 of the snap button 21 is inserted through a hole in a component, such as an electromagnetic shield 29, with the shield 29 resting on the shoulder 26. The shield 29 then may be secured to the snap button 21 by means of a bow washer 31 which is locked into place to hold the shield 29 against the shoulder 26 thereby 4 firmly anchoring the shield to the snap button 21. A locking ring or threaded washer 32 is provided to retain the bow washer 31 in place relative to the snap button 21 and is mounted on a second reduced portion 33 of the body 21, which provides a mounting shoulder 34 of the locking ring 32.

If a shield 29 is to be secured at a predetermined dis tance from the surface of a printed circuit board 25, three or more of the assemblies of the type shown in FIG. 5 may be utilized in order to provide the necessary mounting points for the shield. The same captivating members 10 which are utilized to captivate the screw 16 used to mount the board also perform the additional function of providing a snap-in base for the snap buttons 21 used to support the shield 29 over the printed circuit board 25.

I claim:

1. A locking device for a fastener having a body and a head used to secure sheet material to a base, wherein the body portion of the fastener passes through a hole in the sheet material, the device comprising:

a hollow resilient member having walls defining a shank portion of a dimension substantially conforming to the width of the hole in the sheet material and a fastener head receiving portion of a substantially greater dimension than the dimension of the shank portion, with a common opening between the head re ceiving portion and the shank portion of the member, the walls of the head receiving portion remote from the shank portion extending inwardly toward a central axis of the member and extending downwardly at an acute angle toward the shank portion of the member to form a ledge, the width of the opening defined by the edges of the ledge being less than the width of the head of the fastener, with the width of the head receiving portion being at least as great as the width of the head of the fastener, whereupon insertion of the fastener into the head receiving portion causes the walls of the head receiving portion to be cammed outwardly to allow the head of the fastener to pass therethrough, whereupon the head receiving portion tends to resume its original configuration thereby captivating the fastener within the head receiving portion.

2. The combination according to claim 1 wherein the ledge and the walls defining the fastener head receiving portion include at least one slot therein to facilitate the expansion of the ledge under the camming action caused by the insertion of a fastener therein.

3. A device according to claim l wherein the member has at least one slot extending substantially parallel to the axis thereof, the slot formed therethrough to enable deformation of the shank portion to permit insertion of the member into the hole in the sheet material and to more readily per-mit the outward camming of the ledge of the head receiving portion upon insertion of the fastening device therein.

4. The combination according to claim 3 wherein member is of a substantially hollow cylindrical configuration and the outside diameter of the shank portion is slightly greater than the inside diameter of the hole in the sheet material, so that upon insertion of the member into the hole the tendency of the member to retain its original shape causes the outer sides of the shank portion to firmly engage the edges of the hole.

5. The combination according to claim 4 wherein the shank portion is of suflicient length to extend through the hole in the sheet material and carries at the end remote from the head receiving portion a rib portion flaring outwardly from the axis of the member so that when the member is inserted into the hole, the rib portion extends outwardly over the sheet portion at the edges of the hole to impede removal of the member from the hole.

6. A combination locking device and snap receptacle for captivating a fastener having a shank and a relatively wider head and for providing a snap receptacle for a button having a shank and a relatively Wider base in which the fastener is used to secure a sheet material to a base, with the fastener passing through a hole in the sheet material, the device comprising;

a hollow, cylindrical member having a first portion of a predetermined outside diameter and an inside diameter suflicient to accommodate the shank of the fastener, and with a fastener head and button base receiving chamber of a greater predetermined diameter formed of resilient material and having a slot extending axially therethrough, the axial length of the first portion being such as to permit insertion of the first portion through the sheet material, the end of the receiving chamber remote the first portion including an inwardly and downwardly extending portion forming a ledge causing the opening in the chamber to be of less diameter than the width of the head of a fastener and less than the width of the base of a button adapted to be inserted into the chamber, the distance from the inner edge of the ledge to the bottom of the chamber adjacent the first portion of the member being sufiicient to accommodate the head of the fastener and the base portion of the snap button, so that the device captivates a fastener and button once they have been inserted therein. 7. The device according to claim 6 wherein the outside diameter of the first portion in an undistorted configuration is greater than the inside diameter of the hole in the sheet material, with the slot being of sufiicient width to permit compression of the first portion by an amount to permit insertion of the first portion into the hole, so that upon release, the member tends to revert to its undistorted configuration, firmly engaging the edge of the hole.

8. The device according to claim 6 wherein the base of the button is adapted to be inserted into the chamber after the fastener is inserted therein.

9. The device according to claim 6 wherein the chamber includes at least one additional slot therein to facilitate expansion of the ledge under the camming action of the fastener head and button base upon insertion thereof into the chamber.

References Cited UNITED STATES PATENTS 1,074,247 9/1913 Colegate 242l6 2,097,988 11/1937 Ross 24216X 3,473,203 10/1969 Dzus 1'5169X BERNARD A. GELAK, Primary Examiner US. Cl. X.R. 15 169 

